Better fix for snprintf non-termination on windows.

core/include/fxcrt/fx_system.h

 // Copyright 2014 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
  
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #ifndef _FX_SYSTEM_H_
 #define _FX_SYSTEM_H_
 #define _FX_WIN32_DESKTOP_              1
 #define _FX_LINUX_DESKTOP_              4
@@ skipping 119 matching lines @@
 #ifdef _DEBUG
 #define ASSERT FXSYS_assert
 #else
 
 #define ASSERT(a)
 #endif
 #endif
 #define FX_MAX(a, b) (((a) > (b)) ? (a) : (b))
 #define FX_MIN(a, b) (((a) < (b)) ? (a) : (b))
 #define FX_PI   3.1415926535897932384626433832795f
+
+// NOTE: never trust the return value from snprintf(), but provide versions
+// that always NUL-terminate.
 #if _FXM_PLATFORM_ == _FXM_PLATFORM_WINDOWS_

[brucedawson, 2015/04/10 18:03:02]

Consider making times version limited. When VS 2015 comes out we can switch to
the standard versions, and eventually eliminate this platform-specific mess. You
can do this by adding:

&& _MSC_VER < 1900

This would apply to the definition as well as the declaration.

[Tom Sepez, 2015/04/10 18:23:40]

Done.

-#define FXSYS_snprintf  _snprintf
-#define FXSYS_vsnprintf _vsnprintf
+void FXSYS_snprintf(char *str, size_t size, const char* fmt, ...);

[brucedawson, 2015/04/10 18:03:02]

Consider adding SAL annotations that let /analyze do parameter checking. The
Linux versions will catch most bugs, but some format-string mismatches are
compiler specific. To do this just put _Printf_format_string_ in front of 'const
char*'. This may require #include <sal.h> - I can check that.

Not crucial, but it can be valuable, especially for 64-bit builds.

[Tom Sepez, 2015/04/10 18:23:40]

Done.

+void FXSYS_vsnprintf(char *str, size_t size, const char* fmt, va_list ap);
 #else
-#define FXSYS_snprintf  snprintf
-#define FXSYS_vsnprintf vsnprintf
+#define FXSYS_snprintf  (void) snprintf
+#define FXSYS_vsnprintf (void) vsnprintf
 #endif
+
 #define FXSYS_sprintf   DO_NOT_USE_SPRINTF_DIE_DIE_DIE
 #define FXSYS_vsprintf  DO_NOT_USE_VSPRINTF_DIE_DIE_DIE
 #define FXSYS_strchr    strchr
 #define FXSYS_strlen    strlen
 #define FXSYS_strncmp   strncmp
 #define FXSYS_strcmp    strcmp
 #define FXSYS_strcpy    strcpy
 #define FXSYS_strncpy   strncpy
 #define FXSYS_strstr    strstr
 #define FXSYS_FILE              FILE
@@ skipping 158 matching lines @@
 
 #else  // _FXM_PLATFORM_ == _FXM_PLATFORM_WINDOWS_
 
 #if !defined(PRIuS)
 #define PRIuS "Iu"
 #endif
 
 #endif
 
 #endif